René Descartes -A Discourse on the MethodIn this book Descartes teaches how to use reason to solve problems, how to think clearly and how to approach complex problems. For example, he gives the following rules: 1. never accept anything for true which you do not clearly know to be such 2. divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution 3 commence with objects the simplest and easiest to know, ascending by little and little, to the knowledge of the more complex 4. make enumerations so complete, and reviews so general, that you might be assured that nothing was omitted.Descartes uses a clear language, and deals with maths, geometry, optics, God, man, biology etc.

The Collected Dialogues of PlatoPlato was a supreme writer, and a deep thinker. He talks about Socrates, who used to say : "all I know is that I know nothing". Socrates helped people to give birth to the ideas which, he said, were already in their minds. In later Dialogues, Plato criticizes some theories found in earlier Dialogues.

David Hume - An Enquiry Concerning Human Understanding

This is a very challenging and stimulating reading. How much do we understand? Can we be really sure of anything? Hume is a skeptic, but he's also smart, and wouldn't say stupid things. He reflects on timeless subjects, like the concept of space, time, and infinite. He inspires and fosters new ideas in the reader.

Beyond Good and Evil by Friedrich Nietzsche

Nice was mental, totally different, occasionally funny. In this book he writes about philosophers, nations, music and literature; it looks like he wrote about these topics all his life. Most of the time he's polemical, he hates rational philosophy, and he is a philology scholar. He talks about the Germans as a nation, and compares them to the Italians, French, English. He has a very low opinion of women, and he never hides his unorthodox ideas. He's polemical and hateful most of the time. He compares the gentile southern European spirit to the barbaric Nordic spirit. He gives a different perspectives of the world, and gives different insights on common topics of conversation (for example, he says that love is a feminine and weak passion, as females think that they can solve everything through love; then he says that Jesus was longing for love, he offered to humanity a God of love, and that he went to the extent of dying in order to get from other people what he wanted).

History of Western Philosophy by Bertrand Russell

Russell goes straight to the core of philosophical questions with a plain language. He talks about things that interest him, he rates, mocks, criticized and derides some philosophers. He analyzes the most difficult topics ever with a clear language. He fictions dialogs and examples to make this book easy to understand. He loves some philosophers, he hates other ones, he makes the reader think and laugh. Russell read mountains of books before writing this history, and was a genius in many fields (he estimated his own IQ as 180).

Dialogues and Essays by Seneca

Seneca explains the Stoic doctrine. A true Stoic despises physical pleasures, improves his spirit and pursues only knowledge, philosophy and science. Time is short, and the great minds of the past are always accessible to us through their books. The only bad thing that can happen to a true Stoic is to loose his/her virtue. When evil people harm and torture a stoic, the evil people harm themselves, because they loose their virtue by doing something bad; on the other hand, the stoics who suffer physical pains are always happy, because they don't harm anybody and keep their virtue. Stoics use their reason, therefore they are never angry. Seneca warns that it's hard to be Stoics and wealthy at the same time, but it's possible, if you work extra hard.